""" Experimental module for subtitles support. """

import re

import numpy as np

from moviepy.tools import cvsecs
from moviepy.video.VideoClip import TextClip, VideoClip


class SubtitlesClip(VideoClip):
    """ A Clip that serves as "subtitle track" in videos.
    
    One particularity of this class is that the images of the
    subtitle texts are not generated beforehand, but only if
    needed.

    Parameters
    ==========

    subtitles
      Either the name of a file, or a list
    encoding
      Optional, specifies srt file encoding.
      Any standard Python encoding is allowed (listed at https://docs.python.org/3.8/library/codecs.html#standard-encodings)

    Examples
    =========
    
    >>> from moviepy.video.tools.subtitles import SubtitlesClip
    >>> from moviepy.video.io.VideoFileClip import VideoFileClip
    >>> generator = lambda txt: TextClip(txt, font='Georgia-Regular', fontsize=24, color='white')
    >>> sub = SubtitlesClip("subtitles.srt", generator)
    >>> sub = SubtitlesClip("subtitles.srt", generator, encoding='utf-8')
    >>> myvideo = VideoFileClip("myvideo.avi")
    >>> final = CompositeVideoClip([clip, subtitles])
    >>> final.write_videofile("final.mp4", fps=myvideo.fps)
    
    """

    def __init__(self, subtitles, make_textclip=None, encoding=None):

        VideoClip.__init__(self, has_constant_size=False)

        if isinstance(subtitles, str):
            subtitles = file_to_subtitles(subtitles, encoding=encoding)

        # subtitles = [(map(cvsecs, tt),txt) for tt, txt in subtitles]
        self.subtitles = subtitles
        self.textclips = dict()

        if make_textclip is None:
            make_textclip = lambda txt: TextClip(
                txt,
                font="Georgia-Bold",
                fontsize=24,
                color="white",
                stroke_color="black",
                stroke_width=0.5,
            )

        self.make_textclip = make_textclip
        self.start = 0
        self.duration = max([tb for ((ta, tb), txt) in self.subtitles])
        self.end = self.duration

        def add_textclip_if_none(t):
            """ Will generate a textclip if it hasn't been generated asked
            to generate it yet. If there is no subtitle to show at t, return
            false. """
            sub = [
                ((ta, tb), txt)
                for ((ta, tb), txt) in self.textclips.keys()
                if (ta <= t < tb)
            ]
            if not sub:
                sub = [
                    ((ta, tb), txt)
                    for ((ta, tb), txt) in self.subtitles
                    if (ta <= t < tb)
                ]
                if not sub:
                    return False
            sub = sub[0]
            if sub not in self.textclips.keys():
                self.textclips[sub] = self.make_textclip(sub[1])

            return sub

        def make_frame(t):
            sub = add_textclip_if_none(t)
            return self.textclips[sub].get_frame(t) if sub else np.array([[[0, 0, 0]]])

        def make_mask_frame(t):
            sub = add_textclip_if_none(t)
            return self.textclips[sub].mask.get_frame(t) if sub else np.array([[0]])

        self.make_frame = make_frame
        hasmask = bool(self.make_textclip("T").mask)
        self.mask = VideoClip(make_mask_frame, ismask=True) if hasmask else None

    def in_subclip(self, t_start=None, t_end=None):
        """ Returns a sequence of [(t1,t2), txt] covering all the given subclip
        from t_start to t_end. The first and last times will be cropped so as
        to be exactly t_start and t_end if possible. """

        def is_in_subclip(t1, t2):
            try:
                return (t_start <= t1 < t_end) or (t_start < t2 <= t_end)
            except:
                return False

        def try_cropping(t1, t2):
            try:
                return (max(t1, t_start), min(t2, t_end))
            except:
                return (t1, t2)

        return [
            (try_cropping(t1, t2), txt)
            for ((t1, t2), txt) in self.subtitles
            if is_in_subclip(t1, t2)
        ]

    def __iter__(self):
        return iter(self.subtitles)

    def __getitem__(self, k):
        return self.subtitles[k]

    def __str__(self):
        def to_srt(sub_element):
            (ta, tb), txt = sub_element
            fta = cvsecs(ta)
            ftb = cvsecs(tb)
            return "%s - %s\n%s" % (fta, ftb, txt)

        return "\n\n".join(to_srt(s) for s in self.subtitles)

    def match_expr(self, expr):

        return SubtitlesClip(
            [e for e in self.subtitles if re.findall(expr, e[1]) != []]
        )

    def write_srt(self, filename):
        with open(filename, "w+") as f:
            f.write(str(self))


def file_to_subtitles(filename, encoding=None):
    """ Converts a srt file into subtitles.

    The returned list is of the form ``[((ta,tb),'some text'),...]``
    and can be fed to SubtitlesClip.

    Only works for '.srt' format for the moment.
    """

    times_texts = []
    current_times = None
    current_text = ""
    with open(filename, "r", encoding=encoding) as f:
        for line in f:
            times = re.findall("([0-9]*:[0-9]*:[0-9]*,[0-9]*)", line)
            if times:
                current_times = [cvsecs(t) for t in times]
            elif line.strip() == "":
                times_texts.append((current_times, current_text.strip("\n")))
                current_times, current_text = None, ""
            elif current_times:
                current_text += line
    return times_texts
